only support > php 7.1

lokielse · lokielse · commit 797c6e2d8b82 · 2018-03-30T15:29:18.000+08:00
diff --git a/.travis.yml b/.travis.yml
@@ -1,10 +1,7 @@
 language: php
 
 php:
-  - 5.5
-  - 5.6
-  - 5.6
-  - 7.0
+  - 7.1
 
 before_script:
   - composer install -n --dev --prefer-source
